Stable granular foam control agent comprising a silicone antifoam compound and glycerol

ABSTRACT

The present invention provides stable, free-flowing foam-control agent in granular form, comprising a silicone antifoam compound, a carrier material, an organic coating material, characterized in, that they contain glycerol, at a weight ratio with the silicone antifoam compound of 1:4 to 2:1. The present invention also provides detergent compositions containing said foam control agent.

TECHNICAL FIELD

The present invention is concerned with foam control agents in granularform and with detergent compositions containing such agents.

BACKGROUND

It has become common practice in the detergent industry to include indetergent compositions materials which are intended to control theamount of foam produced during a washing cycle in a washing machine.

Indeed, excessive sudsing has been found to interfere negatively withthe action of the wash liquor upon the fabrics.

Silicone antifoam agents have been found to be particularly effectivespecies, and efforts have been directed to increase the stability ofsuch agents upon prolonged storage of the detergent compositionscontaining them.

In GB 1,492,339, it has been proposed to coat silicone antifoam agentswith an organic material which is a water soluble or water dispersible,substantially non-surface active, detergent-impermeable material e.g.gelatin, agar or certain reaction products of tallow alcohol andethylene oxide.

In EP-A-210 721, it has been proposed to coat silicone antifoam agentswith water-insoluble fatty acid or fatty alcohols, and in EP-A-210 731it has been disclosed to coat silicone antifoam agents with a monoesterof glycerol and a fatty acid.

While such antifoam agents in granulate form appear to exhibit desirablestability upon storage, when incorporated in detergent compositions, ithas been found that such antifoam granulates were not ideally suited foran easy incorporation into detergent compositions in powder form, suchas dry-mixing.

It is thus the object of the present invention to provide storage-stablefoam controlling agents, in the form of granulates which are freeflowing and easily processable into a detergent composition.

SUMMARY OF THE INVENTION

The present invention provides a stable, free-flowing foam-control agentin granular form for inclusion in a detergent composition in powderform, comprising a silicone antifoam compound, a carrier material,preferably starch, an organic coating material, characterized in, thatit contains glycerol, at a weight ratio with the silicone antifoamcompound of 1:4 to 2:1.

The present invention also provides detergent compositions containing asurface-active agent, said foam control agent, and optionally otherdetergent ingredients.

DETAILED DESCRIPTION OF THE INVENTION The Silicone Antifoam Compound

The silicone antifoam compound is present in the foam-control agents ofthe invention, at levels of from 5% to 20% by weight, preferably 8% to15% by weight.

In industrial practice, the term "silicone" has become a generic termwhich encompasses a variety of relatively high-molecular-weight polymerscontaining siloxane units and hydrocarbyl groups of various types.Generally, the silicone suds-controllers can be described as siloxaneshaving the general structure: ##STR1## where each R independently can bean alkyl or an aryl radical. Examples of such substituents are methyl,ethyl, propyl, isobutyl, and phenyl. Preferred polydiorganosiloxanes arepolydimethylsiloxanes having trimethylsilyl endblocking units and havinga viscosity at 25° C. of from 5×10⁻⁵ m² /s to 0.1 m² /s i.e. a value ofn in the range 40 to 1500. These are preferred because of their readyavailability and their relatively low cost.

A preferred type of silicone antifoam agent useful in the compositionsherein comprises a mixture of an alkylated siloxane of the typehereinabove disclosed and solid silica.

The solid silica can be a fumed silica, a precipitated silica or asilica made by the gelformation technique. The silica particles suitablyhave an average particle size of from 0.1 to 50 m, preferably from 1 to20 m and a surface area of at least 50 m² /g. These silica particles canbe rendered hydrophobic by treating them with dialkylsilyl groups and/ortrialkylsilyl groups either bonded directly onto the silica or by meansof a silicone resin. It is preferred to employ a silica the particles ofwhich have been rendered hydrophobic with dimethyl and/or trimethylsilyl groups. Silicone antifoams employed in a foam control agentaccording to the invention suitably have an amount of silica in therange of 1 to 30% (more preferably 2.0 to 15%) by weight of the totalweight of the silicone antifoam resulting in silicone antifoams havingan average viscosity in the range of from 2×10⁻⁴ m² /s to 1 m² /s.Preferred silicone antifoams may have a viscosity in the range of from5×10⁻³ m² /s to 0.1 m² /s. Particularly suitable are silicone antifoamswith a viscosity of 2×10⁻² m² /s or 4.5×10⁻² m² /s.

The Carrier Material

The carrier material for use herein provides the solid basis on whichthe silicone antifoam agent, the organic coating material, and theglycerol are deposited during manufacture; the carrier material musttherefore be in the form of solid particles, which are compatible withdetergent ingredients, are water-soluble or water-dispersible tofacilitate the dispersion of the silicone antifoam agent in the aqueousliquor during the wash cycle, and are capable to absorb or adsorb thesilicone antifoam agent.

The carrier material is present in the present foam control agents atlevels of from 40% to 80% by weight, preferably 55% to 65% by weight.

A preferred carrier material for use in foam control agents according tothe invention is starch, native or chemically modified both hot or coldgelling in water; other suitable materials are kieselguhur and Fuller'searth.

It is also possible to choose carrier particles for use herein, amongingredients which themselves play an active role in the laundering orwashing process. Examples of such materials are zeolites, sodiumtripolyphosphate (STPP) particles, sodium sulphate, sodium carbonate,carboxymethylcellulose and clay minerals.

The Organic Coating Material

The organic coating material is present at levels of from 5 to 30% ofthe antifoam agents according to the invention, preferably from 8% to22% by weight.

Organic coating material suitable for use in the granules of the presentinvention, can be water soluble/dispersible species, water-insolublespecies, or a mixture thereof.

Water-soluble or water-dispersible coating materials must be impermeableto detergent and must be substantially non-surface active. Bysubstantially non-surface active is meant that the coating material,itself, does not interact with the silicone material in such fashionthat it is emulsified or otherwise excessively dispersed throughout anaqueous medium, rather than at the air/water interface.

A wide variety of coating materials having the requisitesolubility/dispersibility characteristics and the essential features ofbeing non-surface active and detergent-impermeable are known. Forexample, the high-molecular-weight Carbowaxes ("Carbowax" is a trademark) which have substantially not surface-active characteristics areuseful herein. Examples of this type of material include thepolyethyleneglycols having a molecular weight of from about 1,500 toabout 10,000, especially about 4,000. Highly ethoxylated fatty alcoholssuch as tallow alcohol condensed with about 25 molar proportions ofethylene oxide are useful herein. Other alcohol condensates containingextremely high ethoxylate proportions (ca 80) are also useful herein.Such high ethoxylates apparently lack sufficient surface-activecharacteristics to interact or otherwise interfere with the desiredsuds-control properties of the silicone agents herein. A particularlypreferred ethoxylated coating material herein is tallow alcoholcondensed with about 80 molar proportions of ethylene oxide, andabbreviated TAE₈₀.

A variety of other materials useful as water-soluble/dispersible coatingagents herein may also be mentioned: gelatin; agar; gum arabic; andvarious algae-derived gels.

Water-insoluble organic materials suitable for use in a foam controlagent according to the invention are water-insoluble fatty acids, fattyalcohols, fatty acid esters and mixtures thereof. Fatty acids or fattyalcohols are species which have from 10 to 20 carbon in their alkylchain.

Suitable fatty acids are saturated or unsaturated and can be obtainedfrom natural sources such as, for example, plant or animal esters (e.g.palm oil, coconut oil, babassu oil, safflower oil, taloil, castor oil,tallow and fish oils, grase, and mixtures thereof) or can besynthetically prepared for example via the oxidation of petroleum or byhydrogenation of carbon monooxide via the Fisher-Tropsch process.Examples of suitable fatty acids for use in the present inventioninclude capric, lauric, myristic, palmitic, stearic, arachidic andbehenic acid.

Preferred is stearic acid. Also preferred is tallow (C₁₆ -C₁₈) fattyacid. Alcohols derived from the above-mentioned fatty acids are suitablefor the foam control agents herein, stearic alcohol and tallow (C₁₆-C₁₈) alcohol being preferred.

Esters of the above-mentioned fatty acids with C₁₋₃ alcohols are alsosuitable, such as ethyl myristate, ethyl stearate, methyl palmitate, andglycerol mono stearate, this latter species being especially preferred.

Among the above water-insoluble fatty materials, stearyl acid andstearyl alcohol are especially preferred. These materials are preferredbecause of their good performance, easy availability and suitablemelting point. The melting points of stearic acid and stearyl alcoholare 71.5° and 59.4° C. respectively at which temperatures they areinsoluble in water. These materials do not appear to interfere with theeffectiveness of the silicone antifoam when it is released into thewashing liquor.

Mixtures of the above water-soluble/dispersible coating agents and ofthe above water-insoluble organic materials herein are also suitable. Apreferred mixture is stearyl alcohol and TAE₈₀.

The amount of organic coating material employed in the foam controlagents herein should be no less than 1 part organic coating material perpart of silicone antifoam. It is preferred to employ the organic coatingmaterial and the silicone antifoam in a weight ratio in the range 5:1 to1:1, more preferably in the range 4:1 to 2:1.

The glycerol is a key ingredient of the foam control agents herein; itis believed to strengten the adsorption of silicone antifoam compound tothe carrier particles. Glycerol is present at a weight ratio of 1:4 to2:1 with the silicone antifoam agent, and at levels of from 2 to 20%,preferably 4% to 10% of the foam control agents herein.

Optional Ingredients

The foam control agents may comprise, in addition to the essentialingredients described hereinabove, optional ingredients, such as waxes,and anti-caking agents.

Preferred waxes are of mineral origin, especially those derived frompetroleum, including microcrystalline and oxidised microcrystallinepetroleum waxes and paraffin waxes. However synthetic waxes, or naturalwaxes such as Montan waxes, beeswax, candelilla or carnauba waxes mayalso be used as may a mixture of any of these waxes. Whatever wax isused it is preferred that its melting point is between 35° and 70° C. sothat it is readily liquifiable.

Suitable anti-caking agents include alkoxylated nonionic surfactantssuch as described hereinafter.

Making Process for the Anti-foam Agent of the Invention

The process is as follows:

The silicone antifoam compound and the glycerol, at a weight ratio suchas presently claimed, are mixed together and the mixture is added to thecarrier material, which is preferably starch; the mixing then takesplace in an Eirich mixer. During the mixing, the temperature raises dueto the agitation. When the temperature reaches a value in the range offrom 30° to 35° C., the organic coating material, is added in the moltenstate (e.g. at 85° C., if stearyl alcohol), and the mixing is continuedused until approximately 5 minutes after the melting temperature of theorganic coating agent is reached (56° to 58° C. for stearyl alcohol).

Granulation has then taken place, and the granules are cooled to roomtemperature in a fluid bed.

Detergent Compositions

In another embodiment of the present invention, it is herewith provideda detergent composition in powder form, comprising a surface-activeagent and a foam control agent such as described above. The amount offoam control agents is from 0.25 to 10%, preferably from 0.5 to 3 byweight of the total detergent composition.

Suitable surface-active agents are of the anionic, cationic, non-ionicor amphoteric type, or mixtures thereof. Suitable anionic organicdetergent surfactants include alkali metal soaps of higher fatty acids,alkyl aryl sulphonates, for example sodium dodecyl benzene sulphonate,long chain (fatty) alcohol sulphates, olefine sulphates and sulphonates,sulphated monoglycerides, sulphated ethers, sulphosuccinates, alkanesulphonates, phosphate esters, alkyl isothionates, sucrose esters andfluorosurfactants. Suitable cationic organic detergent surfactantsinclude-alkyl-amine salts, quaternary ammonium salts, sulphonium saltsand phosphonium salts. Suitable non-ionic organic surfactants includecondensates of ethylene oxide with a long chain (fatty) alcohol or fattyacid, for example C₁₄₋₁₅ alcohol, condensed with 7 moles of ethyleneoxide (Dobanol® 45-7), condensates of ethylene oxide with an amine or anamide, condensation products of ethylene and propylene oxides, fattyacid alkylol amides and fatty amine oxides. Suitable amphoteric organicdetergent surfactants include imidazoline compounds, alkylaminoacidsalts and betaines.

The detergent compositions herein preferably also contain a builder,which is preferably a non-phosphate species; accordingly, the builderherein preferably is selected from aluminosilicate ion exchangers(zeolites), and water-soluble monomeric or oligomeric carboxylatechelating agents such as citrates, succinates, oxydisuccinates, as wellas mixtures of the above species.

Other suitable builder materials include alkali metal carbonates,bicarbonates and silicates, organic phosphonates, amino polyalkylenephosphonates and amino polycarboxylates, ethylene diamine tetraaceticacid and nitrilotriacetic acid. Other suitable water-soluble organicsalts are the homo- or co-polymeric polycarboxylic acids or their saltsin which the polycarboxylic acid comprises at least two carboxylradicals separated from each other by not more than two carbon atoms.Polymers of this type are disclosed in GB-A-1,596,756. Examples of suchsalts are polyacrylates of MW 2000-5000 and their copolymers with maleicanhydride, such copolymers having a molecular weight of from 20,000 to70,000, especially about 40,000.

Other ingredients which typically form part of a detergent compositionin powder form include bleaching agents, such as sodium perborate andpercarbonate, bleach activators, anti redeposition agents such ascarboxymethyl cellulase, enzymes, brighteners, fabric softening clays,perfumes, dyes, pigments.

EXAMPLE

A foam-control agent in granular form is produced, having the followingcomposition:

    ______________________________________                                        ingredients       percent by weight                                           ______________________________________                                        Silicone antifoam compound*                                                                     12%                                                         Glycerol          12%                                                         Stearyl Alcohol   18%                                                         Starch            58%                                                         ______________________________________                                         *Polydimethyl siloxane/fumed silica X2/3419 from Dow Corning             

A quantity of 3.4 kg of the above foam control agent in granular form isproduced, starting from 0.4 kg silicone antifoam agent, 0.4 kg glycerol,2 kg starch, and 0.6 kg stearyl alcohol in molten state. The process isdescribed hereinabove.

The above granulates are crispy and free flowing; they are incorporatedin a detergent composition in powder form, by dry-mixing.

Thanks to the quality of the granulates, this incorporation into thedetergent composition does not raise any processing difficulty.

EXAMPLE II

Foam control agents according to the invention can be prepared, whereintallow fatty acid is used instead of stearyl alcohol; such a foamcontrol agent has been prepared, according to the following composition:

    ______________________________________                                        Ingredients       percent by weight                                           ______________________________________                                        Silicone antifoam compound*                                                                     12%                                                         Glycerol           6%                                                         Tallow fatty acid 15%                                                         Starch            67%                                                         ______________________________________                                    

Typical detergent compositions in powder form in which the presentantifoam agents in granular form are included have the followingformulae:

    ______________________________________                                                      (all levels in % by weight)                                     Ingredients     Ex. III   Ex. IV                                              ______________________________________                                        LAS             8.00      6.50                                                TAS             2.50      3.35                                                FA45E7          5.00      2.00                                                Na citrate/citric acid                                                                        --        12.00                                               Zeolite 4A      24.00     16.00                                               Copolymer AA/MA 5.00      3.50                                                Phosphonate     0.60      --                                                  EDTA            0.25      0.30                                                Na carbonate    17.00     10.00                                               Silicate (R = 2)                                                                              2.00      2.50                                                CMC             0.50      --                                                  Clay            --        8.50                                                PB1             13.00     --                                                  PB4             --        12.00                                               TAED            5.70      3.20                                                Enzyme          1.70      1.70                                                Foam control agent                                                                            0.70      0.80                                                Minors + water  balance to 100%                                               ______________________________________                                    

The abbreviations for the individual ingredients have the followingmeaning:

LAS: sodium salt of linear dodecyl benzene sulfonate

TAS: sodium salt of tallow alcohol sulfate

FA45E7: fatty alcohol (C₁₄ -C₁₅) ethoxylated with about 7 moles ofethylene oxide

Clay: smectite clay

Zeolite 4A: sodium salt of zeolite 4A with average particle size between1-10 micrometer

Copolymer AA/MA: copolymer of acrylic acid and maleic acid

CMC: carboxymethylcellulose

Phosphonate: sodium salt of ethylenediamine tetramethylene phosphonicacid

EDTA: sodium salt of ethylenediamine tetra acetate

PB1: NaBO2.H2O2 (Sodium Perborate Monohydrate)

PB4: NaBO2.H2O2.3H2O (Sodium Perborate Tetrahydrate).

TAED: tetra acetyl ethylene diamine

I claim:
 1. A stable, free-flowing foam-control agent in granular formfor the inclusion in a detergent composition in powder form, saidfoam-control agent comprising:a. from 5 to 20% by weight of a siliconeantifoam compound, b. from 40 to 80% by weight of a carrier material, c.from 5% to 30% by weight of an organic coating material selected from:i.water-soluble or water-dispersible, detergent impermeable, substantiallynon-surface-active materials; ii. water-insoluble materials selectedfrom fatty acids, fatty alcohols, fatty acid esters, and mixtures ofsaid water-insoluble materials; and iii. mixtures of said water-solubleor water-dispersible and water-insoluble materials; and d. from at leastabout 4% to 20% glycerol in a weight ratio of glycerol to siliconeantifoam compound of 1:4 to 2:1.
 2. A foam control-agent according toclaim 1 wherein the silicone antifoam compound comprises apolydiorganosiloxane and solid silica.
 3. A foam-control agent accordingto claim 1 wherein the carrier material is starch.
 4. A foam-controlagent according to claim 1 wherein the water-soluble/dispersible,organic coating agent is selected from highly ethoxylated fattyalcohols, condensed with about 25 molar to 80 molar proportions ofethylene oxide.
 5. A foam-control agent according to claim 4 wherein thewater-insoluble fatty acids or fatty alcohols, or mixtures thereof havea carbon chain length of from 12 to 20 carbon atoms and a melting pointin the range of from 45° C. to 80° C.
 6. A foam-control agent accordingto claim 3 wherein the organic coating agent is selected from stearicacid, stearyl alcohol, tallow fatty acid, tallow fatty alcohol, tallowalcohol condensed with about 80 molar proportions of ethylene oxide, andmixtures thereof.
 7. A method of making a foam-control agent accordingto claim 1, wherein the silicone antifoam agent and glycerol are mixedtogether and added to the carrier material, the organic coating agent isthen added, and mixing/granulation follows.
 8. A detergent compositionin powder form comprising up to 90% by weight of a surface-active agentselected from a group comprising anionic, cationic, non-ionic, oramphoteric agents or mixtures thereof, and a foam-control agentaccording to claim 1, 2, 3, 5, 6, 7, 11, or
 12. 9. A foam-control agentaccording to claim 2 wherein the carrier material is starch.
 10. Afoam-control agent according to claim 1 wherein the organic coatingagent is selected from stearic acid, stearyl alcohol, tallow fatty acid,tallow fatty alcohol, tallow alcohol condensed with about 80 molarproportions of ethylene oxide, and mixtures thereof.
 11. A stable,free-flowing foam-control agent in granular form and suitable forinclusion in a powder-form detergent composition, which foam-controlagent comprises:a. from 8% to 15% by weight of a silicone antifoam agentcomprising a mixture of solid silica and a polydimethylsiloxane polymerwith trimethylsilyl endblocking units; b. from 4% to 10% by weight ofglycerol admixed with said silicone antifoam agent to form asilicone/glycerol admixture having a weight ratio of glycerol tosilicone antifoam agent of from 1:4 to 2:1; c. from 55% to 65% by weightof a carrier material with which the silicone/glycerol admixture iscombined to form particles, said carrier material being selected fromstarch, kieselguhr and Fuller's earth; and d. from 8% to 22% by weightof an organic coating material for said particles, which coatingmaterial is selected from stearic acid, stearyl alcohol, tallow fattyacid, tallow fatty alcohol, tallow alcohol condensed with about 80 molarproportions of ethylene oxide, and mixtures thereof, and which saidorganic coating material is used in a weight ratio of coating materialto silicone antifoam agent ranging from 5:1 to 1:1.